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Chitosan-DNA complexes: charge inversion and DNA condensation.

Francesca Amaduzzi1, Francesca Bomboi1, Adalberto Bonincontro1

  • 1Dipartimento di Fisica, Sapienza Università di Roma, P.zzle A. Moro, 2, 00185 Roma, Italy.

Colloids and Surfaces. B, Biointerfaces
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Summary

Chitosan-DNA complexes show reentrant condensation and charge inversion, with aggregate size and structure depending on charge ratio and chitosan length. These findings aid in designing effective gene delivery vectors.

Keywords:
Charge inversionChitosanDNAGene-therapyPolyelectrolytesPolyplexes

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Area of Science:

  • Biomaterials Science
  • Polymer Chemistry
  • Nanotechnology

Background:

  • Biocompatible polyelectrolyte complexes are promising for in vivo delivery of macromolecules.
  • Developing safe, effective non-viral vectors for gene delivery is a key challenge.
  • Chitosan is an emerging polycation material for these applications.

Purpose of the Study:

  • To compare Chitosan-DNA complex aggregation behavior with existing polyelectrolyte complexation models.
  • To characterize the structures of Chitosan-DNA complexes formed at varying conditions.
  • To validate theoretical models for designing gene delivery vectors.

Main Methods:

  • Atomic Force Microscopy (AFM), Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM).
  • Light scattering and electrophoretic mobility techniques.
  • Characterization of complexes at different charge ratios and Chitosan molecular weights.

Main Results:

  • Reentrant condensation and charge inversion observed with increasing polycation/DNA charge ratio.
  • Maximum aggregate size correlated with charge sign inversion, not 1:1 ratio.
  • Aggregate morphology varied: tadpole-like in excess polycation, globular in excess DNA, fiber-like near isoelectric point.
  • Observed phenomena align with theoretical predictions and explain literature findings.

Conclusions:

  • Theoretical models accurately predict Chitosan-DNA complexation behavior.
  • Understanding aggregation mechanisms aids in designing efficient polycation-based gene delivery vectors.
  • Chitosan-DNA complexes offer a tunable platform for genetic material delivery.